One known example of an optical scanning endoscope apparatus detects a luminance level based on reflected light from an object illuminated with light and controls the amount of illumination light in accordance with scanning position by setting the amount of illumination light so that, in the observation image, the light amount is reduced as the luminance level is brighter at the scanning position and is increased as the luminance level is darker at the scanning position (for example, see JP 2010-115391 A (PTL 1)).